1980 304 different?

Hey all,
I'm getting ready to rebuild my 1980 304, but I'm seeing a lot of kits say they only cover up to a 1979 304. Anyone know if there was a major change in 1980 that would make mains, rods, or gasket sets different? Another issue is that the PO heard a rumor that the engine had been swapped, so who knows? I'll probably end up just buying the parts and seeing what happens.

 

No difference as far as I know. Does your VIN show that the Jeep was factory equipped with a 304? At some point, they stopped making 304s, and you may be encountering that in the parts books.

 

No, it came with a 304 since the emissions sticker is still there. But I don't know if it's the original or an older model. I'm almost tempted to start over with a 360, but I don't know where I would find one. And (of course) money is an issue.

 

A good source for a 360 is usualy a grand wagoneer. Rusty ones can be had for under $500, and the scrapped shell can usually fetch some decent $ at a junk yard.

 

And that's another question: What should I change to get better performance / economy? Headers? 4bbl? New cam? I know it would be good to get all the emissions crude off it.

 

If it were mine, I'd rebuild the 304 or go with a 401. If you went with the 401, throw economy out the window. The 401 is a great engine though.

The 360 is basically the same as a 304, except it has a larger bore and different heads. You see a lot of 360s in CJs because the 360 is much more available on the used engine market than the 304. The Wagoneer was produced up until 1991, and almost all of them used the 360.

JMO - I'd probably go TBI on the stock manifold, a cam, do the TFI ignition upgrade, stock exhaust manifolds, quiet dual exhaust. The 304 was so detuned by 1980 that simple, mild changes like that would really wake it up.

Why do you think your engine needs rebuilding?

 

It's just getting "loose" you know? 18 lbs oil pressure at hot idle, tappets making noise, puff of smoke when she fires up. I was goofing off and floored it hard on a right turn and ran it out of oil for WAY too long (15+ seconds). Never been the same since. I don't care that much for economy, since I only drive it 5 miles a day to work. I hate to admit it, but it's really a street rod more than anything. I'm embarrassed to admit that I like it to LOOK like the ultimate trail rig, but RUN like a hot rod. I know, I'm a fake. And in November, I'm going to be driving it from Augusta GA to Seattle WA, so....

 

Just a comment - I'd take the opportunity to do as thorough a diagnosis as possible now, while it's together and running. The puff of smoke when starting is likely due to loose valve guides. Tappets making noise could be because of low hot idle oil pressure.

These engines are notorious for LHIOP. The oil pump gears are in the timing cover, and the timing cover and oil pump adapter are made of aluminum. The aluminum parts wear before the rest of the engine does. You can often cure this problem without rebuilding the engine - the steel mid plate from BullTear can help a lot. At worst, you'd need a new timing cover. I'd measure the pump clearance with plastigage before doing anything drastic.

Had you planned to work on this engine yourself?

 

Tim,
I've rebuilt a few before, so other than no longer having all my tools any more, that's not a problem. I was actually wondering about the oil pump, since it "seems" to take a lot longer for the oil pressure to come back after loss than with the other engines I've had, and the aluminum housing just makes me nervous.
I'm not desperate to rebuild, but I don't want to wait until my crank is nothing but a boat anchor either. My last 304 lost a rod bearing without any warning. I've just had a few engines before that when the oil pressure fell below 20 psi, it was time to start pricing rebuild kits.